Effect of Added Cr₃C₂ on the Microstructure and Mechanical Properties of WC–SiC Ceramics

Abstract:

WC–20 mol% SiC ceramics with added Cr₃C₂ were sintered at 1600°C with a resistance-heated hot-pressing machine. Dense WC–SiC ceramics containing 0.1–0.9 mol% Cr₃C₂ were obtained. Above 1.2 mol% Cr₃C₂, the relative density decreased with increasing Cr₃C₂ content. A small amount of a Nowotny-phase type (Mo₅Si₃C-type) product was formed by the addition of Cr₃C₂, and no Cr₃C₂-based solid solution was found. The WC–20 mol% SiC–Cr₃C₂ ceramics had very fine equiaxed granular WC grains because of inhibited grain growth of WC. The Young’s modulus of the WC–20 mol% SiC–Cr₃C₂ ceramics decreased with increasing Cr₃C₂ content because Cr₃C₂ has a much lower Young’s modulus than WC. Cr₃C₂ addition below 0.9 mol% increased the Vickers hardness from 20.9 to 23.0 GPa, but a larger added amount reduced the Vickers hardness. The hardness of the WC–20 mol% SiC–Cr₃C₂ ceramics and the WC grain size obeyed a Hall–Petch-like relationship, suggesting that the hardness was strongly controlled by the WC grain size. A higher fracture toughness, 6.4 MPa m^1/2, was obtained for the ceramics containing a small amount of Cr₃C₂ than for the binder-free WC. The addition of 0.1–0.3 mol% Cr₃C₂ improved the fracture toughness without reducing the hardness.

• Periodical: Key Engineering Materials (Volumes 656-657)
• Pages: 33-38
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.656-657.33
• Online since: July 2015
• Authors: Akihiro Nino*, Takashi Sekine, Kazuhisa Sugawara, Shigeaki Sugiyama, Hitoshi Taimatsu
• Keywords: Fracture Toughness, Grain Growth Inhibitor, Hardness, Microstructure, Silicon Carbide (SiC), Tungsten Carbide

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